Falling by Doug Wilhelm
Matt and his brother Neal were both star basketball players. Neal was not offered the scholarship he wanted, and decided to “take the year off.” This means that Neal began a life of selling and using drugs. Matt reacts by dropping out of everything and walking after school to avoid going home, to avoid his basketball friends, to avoid his life. He finds his life online a pseudo-life, meeting Katie, a girl who accidentally goes to the same high school, and they become friends after the usual trauma of finding out who each other is.
The brothers have the usual set of clueless parents, caring friends, and problems finding the right path. The story however, is satisfying in a problem-solving, suspenseful plot. Told alternately by Katie and Matt, so we get their viewpoints as well as their friends. The email link can be problematic enough to talk about.
While there is an obvious romance, there is no sex.